This research proposes to define a unique biochemical abnormality in erythrocyte membrane spectrin that is characterstic of and specific to X-linked Duchenne muscular dystrophy. Using the abnormally increased (32P)-phosphorylation of erythrocyte protein band 2 as a marker, methods of peptide mapping and isolation are proposed that involve a number of peptide cleavage techniques. Methods of analysis include gel filtration, stacking polyacrylamide gel electrophoresis and reverse phase high performance liquid chromatography. In addition, applications of monoclonal antibody techniques to analytical and preparative peptide isolations are proposed. This renewal proposal is the next phase of a long term project to define the biochemical defect in Duchenne dystrophy, to determine the pathogenesis of the disease and to use these data to develop diagnostic methods for patients, carriers and fetuses at risk.